Don't Blame the Duodenoscope Elevator, the Channels Are Contaminated as Well: A Systematic Review and Meta-Analysis

Introduction: The elevator mechanism has been suggested as the main reason for multiple outbreaks associated with contaminated reusable patient-ready duodenoscopes. The elevator is difficult to clean even with all precautions, and specially designed brushes are recommended for proper cleaning. However, the narrow channels of the duodenoscope might pose a risk of contamination since they are prone to scratches by the insertion of various accessories creating space for microbes to hide. Our aim is to estimate the contamination rate beyond the elevator of duodenoscopes based on currently available literature. Methods: We searched PubMed, Web of Science, and Embase from January 1, 2010, until October 10, 2020, for studies investigating contamination rates of reprocessed duodenoscope channels and areas beyond the elevator. A random-effects model (REM) based on the proportion distribution was used to calculate the pooled total contamination rate beyond the elevator of reprocessed duodenoscopes. The meta-package (metafor) in RStudio version 3.6.2 was used to conduct the statistical analyses. Heterogeneity between the included studies was analyzed using the inconsistency index (I2) statistics. Publication bias was assessed using the funnel plot and Egger’s regression test. Results: Eight studies including 215 positive cultures from 2,001 samples fulfilled the inclusion criteria. Four studies (50%) originated from the US, 3 studies (37.5%) originated from Europe (Italy, Netherlands, and Austria), and 1 study (12.5%) was conducted in Taiwan. See table 1 for baseline characteristics of the included studies. The total weighted contamination rate was 14.41% ± 0.029 (95% confidence interval [Cl]: 8.70% - 20.13%), see figure 1. I2 was 96.4% indicating high heterogeneity. Egger’s regression test indicated no significant publication bias (Egger’s test of publication bias: p=0.9919). Conclusion: Our analysis indicates that 14.41% of reprocessed patient-ready duodenoscopes may be contaminated unrelated to the elevator. These findings highlight that the elevator mechanism is not the only part of the duodenoscope, which could remain contaminated even after reprocessing. Despite the role of contaminated channels has been studied, more evidence is needed to fully determine the consequences and potential link to patient-to-patient infections. Additionally, guidelines for disinfection units should recommend thorough surveillance of the endoscope channels to minimize endoscope-related infections.Table 1.: Study characteristics of included studies.Figure 1.: Pooled estimates of contamination rates beyond the elevator of patient-ready duodenoscope. CI: confidence interval; prop: proportion.